The present invention relates to a method and apparatus for dispensing and/or positioning strands of wire or cable or other items and in particular to dispensing wire or cable, e.g., for forming a bundle and placement of the bundle.
In the construction industry, it is commonly necessary to position a plurality of wires, cables, or the like along similar paths. Typically, the plurality of wires or cables are formed into a bundle and the bundle is put into position such as by pulling it along a desired path.
Often, a wire cable or bundle path is defined at least partially by a conduit, often an underground or inter-wall conduit, and/or a cable tray. Typically a cable tray has a floor region defined by, e.g., a plurality of beams, ties, plates, etc., and has a depth defined by sidewalls or side members which may be, for example, plates, I-beams, channels and the like. Pulling cables, wires or bundles along conduits or cable trays or other paths often involves a relatively high degree of tension during the pulling process, particularly when the cables are large or heavy. Furthermore, in many situations the tension required for cable pulling may be variable, involving sudden increases or spikes in the pulling tension, sometimes accompanied by sudden decreases. Variability in pulling tension can have serious safety consequences, e.g. if cables, ropes or the like unexpectedly part, and requires a greater pulling force to achieve the desired placement than if such tension spikes could be avoided. Without wishing to be bound by any theory, it is believed that the average tension, and spikes in the pulling tension involved in cable pulling, can be at least partially attributed to factors such as friction between cable and stationary surfaces (including cable tray surfaces, conduit surfaces and surfaces of adjacent cables), and/or flexing of cable, as cable is moved along a non-linear path (either because the desired path is non-linear or because the cable itself has a tendency to kink or revert to a previous cable shape, i.e., has a shape xe2x80x9cmemoryxe2x80x9d).
Accordingly, it would be advantageous to provide a cable pulling system or components thereof which assist in reducing or eliminating spikes in pulling tension and in reducing overall or average tension, such as by avoiding friction or accommodating cable memory. It is believed that it would be particularly advantageous to provide such a system or components which can be relatively easily and inexpensively provided, installed, manipulated and used.
Because wires and cables of the type currently installed come in a wide variety of shapes, sizes, weights and configurations, it would be advantageous to provide a cable system and components which can readily accommodate or be modified to accommodate a wide variety of cable or bundle configurations.
The process of forming and positioning a bundle is particularly difficult when the individual wires or cables in the bundle must have different starting and/or ending points. FIG. 1A illustrates schematically a bundle, consisting of three wires 10, 12, 14 which are, following positioning, intended to extend between beginning and ending terminals 10a, 10b, 12a, 12b, 14a, 14b, respectively. Because, in the example shown, the beginning and ending terminals 10a, 10b, 12a, 12b, 14a, 14b do not coincide for any of the wires 10, 12, 14, the bundle which is to be pulled along the desired pathway is preferably formed as shown in FIG. 1B. Of particular note is that none of the starting or ending points of the three wires 10, 12, 14 occur at the same point along the bundle 16.
According to previous methods, a bundle such as the bundle 16 shown on FIG. 1B would be formed by extracting each length of wire 10, 12, 14, separately. Typically, the wires 10, 12, 14 would each be pulled from a wire spool, measured, such as with a tape measure, and laid on the surface such as the ground or a floor surface. Next, the three wires 10, 12, 14 would be moved lengthwise, relative to each other, until they had the configuration shown in FIG. 1B. At this point, the wires 10, 12, 14 could optionally be permanently or temporarily held together such as by using cable ties or the like. The bundle 16 thus formed would then be in a configuration such that it could be pulled along the desired pathway.
Once the bundle 16 is formed, it is moved to the initial point of the pathway along which it is to be pulled. Typically, it is moved by pulling or carrying the bundle. Next, the bundle is placed along the desired pathway. According to one method a rope is first placed along the desired pathway, one end of the rope is attached to one end of the bundle and the rope is pulled from the other end, thus pulling the bundle along the desired path. In previous devices, cable was sometimes pulled along a path using a motor. Such motors typically have one or a few rates of pull, making it impossible to accurately adjust the rate of pull to the conditions. Typically, the motor was attached to a portion of a relatively massive object, such as a portion of a building, a beam, or a wall. This placed undesirable constraints on where the motor can be positioned so that pulling efficiency was reduced. Pulling efficiency is typically greatest when the pulling apparatus is positioned near one end of the pathway, end of a conduit or cable tray and the like. Because of the need to attach the motor to, e.g., the building, a large amount of time was required to set up the motor to achieve a pull.
The process of pulling each individual wire, measuring each individual wire, and moving the wires until they have the desired configuration relative to each other is labor-intensive and thus expensive. Furthermore, even when starting or ending points coincide, the process is prone to error, particularly when a large number of wires, such as different gauge wires, are used to form the bundle. Additionally, once the bundle is formed, transporting the bundle to the entry point of the pathway along which it is to be pulled is cumbersome.
In some instances, it has been found useful to position one or more rollers along the desired pathway in order to help guide the bundle as it is being moved. In some cases, it is convenient to form a roller from a length of pipe such as PVC pipe 18 (FIG. 2). In order to provide for axial mounting of the pipe 18, endcaps 20 are press-fitted into the ends of the pipe 18. The endcaps 20 may have hubs 22 for axially mounting the rollers thus formed. The rollers formed according to the configuration shown on FIG. 2, however, have been found to be susceptible to permitting the cable which it supports to slip over the end 24 of the roller, thereby often causing the cable to bind or even damaging the cable.
The present invention relates to a method and apparatus which, among other things, reduces the time and effort necessary to form and place bundles, compared to the previous methods used. According to one embodiment of the invention, a clip is provided for holding a roller adjacent, preferably substantially above, a cable tray with provision for quickly releasing the roller from the clip, e.g. for re-positioning the cable from a position above the roller to a position below the roller, such as in or on a cable tray. Preferably the roller may readily move laterally across the width of the cable tray, e.g. to accommodate irregularity or shape memory of a cable and thus reduce or avoid tension spikes.
In one embodiment, a pair of endless tracks can be used to provide for intermediate cable tugging or pulling. When a central beam forms a part of the cable tray, rollers may be positioned using a device for attaching to the central beam such as a roller-holder with resilient or otherwise movable beam-grasping arms. When cable placement makes it desirable to, e.g. laterally position or hold a cable, a cable jack may be used, preferably fitted with plates or similar components for contacting and moving cable 5 while avoiding damage to the cable. In one embodiment a plurality of rollers or sheaves are positioned on a curved or radiused holder for supporting or guiding cables along a nonlinear path. Preferably such radiused sheave device is provided with couplers for quickly and easily positioning and holding the radiused sheave device in the desired location.
According to one embodiment of the present invention, two or more sources of wire are provided on a rack. As used herein xe2x80x9cwirexe2x80x9d refers to any filamentous material, preferably electrical wire or electrical cable, but including also material such as plastic or other non-electrical wire or cable, rope, chain, optic fibers, and the like. One or more of the wires is connected to a counter.
In one embodiment, a rack includes a platform portion and one or more pairs of upstanding arms configured to receive one or more cable axes reel axials so as to facilitate reel rotation while avoiding undesirable axial displacement and preferably so as to facilitate the process of loading or unloading reels with respect to the rack.
A cable bundle is transported near one end of the desired pathway for the bundle. This can be done by transporting the holding spool to such location or by transferring the bundle to a secondary spool which is then moved near one end of the desired pathway. It is also possible to pull the bundle as it is being measured and formed directly into the desired pathway without first storing it on the holding or secondary spool.
Preferably, a rope connected to a drive able pulling spool has been positioned along the desired pathway and connected to one end of the bundle. Upon driving the drive able pulling spool, the rope is wound onto the pulling spool and the bundle is pulled along the pathway formerly occupied by the rope thus positioning the bundle as desired.